Transition-Metal Vacancy Manufacturing and Sodium-Site Doping Enable a High-Performance Layered Oxide Cathode through Cationic and Anionic Redox Chemistry

Triggering the anionic redox chemistry in layered oxide cathodes has emerged as a paradigmatic approach to efficaciously boost the energy density of sodium-ion batteries. However, their practical applications are still plagued by irreversible lattice oxygen release and deleterious structure distortion. Herein, a novel P2-Na_0.76Ca_0.05[Ni_0.23□_0.08Mn_0.69]O₂ cathode material featuring joint cationic and anionic redox activities, where native vacancies are produced in the transition-metal (TM) layers and Ca ions are riveted in the Na layers, is developed. Random vacancies in the TM sites induce the emergence of nonbonding O 2p orbitals to activate anionic redox, which is confirmed by systematic electrochemical measurements, ex situ X-ray photoelectron spectroscopy, in situ X-ray diffraction, and density functional theory computations. Benefiting from the pinned Ca ions in the Na sites, a robust layered structure with the suppressed P2-O2 phase transition and enhanced anionic redox reversibility upon charge/discharge is achieved. Therefore, the electrode displays exceptional rate capability (153.9 mA h g⁻¹ at 0.1 C with 74.6 mA h g⁻¹ at 20 C) and improved cycling life (87.1% capacity retention at 0.1 C after 50 cycles). This study provides new opportunities for designing high-energy-density and high-stability layered sodium oxide cathodes by tuning local chemical environments.     

Accessible Li Percolation and Extended Oxygen Oxidation Boundary in Rocksalt-like Cathode Enabled by Initial Li-deficient Nanostructure

Disordered rocksalt cathodes have shown attractive electrochemical performance via oxygen redox, but are limited by a necessary Li-excess level above the percolation threshold (x > 1.09 in Li_xTM_2-xO₂, TM = transition metals) to obtain electrochemical activity. However, a relatively low-Li content is essential to alleviate excessive oxygen charge compensation in rocksalt oxides. Herein, taking the homogeneous Li₂MnO₃ and LiMn₂O₄ as the starting point, disordered rocksalt-like cathodes are prepared with initial Li-deficient nanostructures, cation vacancies, and partial spinel-type structures that provide a solution for the acquisition of fast Li⁺ percolation channels under Li-deficient condition. As a result, the prepared sample exhibits high initial discharge capacity (363 mAh g⁻¹) and energy density (1081 Wh kg⁻¹). Advanced spectroscopy and in situ measurements observe highly reversible charge compensation during electrochemical process and assign coupled Mn- and O-related redox contribution. Theoretical calculations also suggest the novel and chemical reversible trapped molecular O₂ model in the rocksalt structure with vacancies, demonstrating a dual role of Li-deficient structure in promoting cationic oxidation and extending reversible oxygen redox boundary. This work is expected to breakthrough the existing ideas of oxygen oxidation and opens up a higher degree of freedom in the design of disordered rocksalt structures.     

Manipulating the Local Electronic Structure in Li-Rich Layered Cathode Towards Superior Electrochemical Performance

Manipulating the local electronic structure is employed to address the capacity/voltage decay and poor rate capability of Li-rich layered cathodes (LLOs) via the dual-doping of Na⁺ and F⁻ ions, as well as the regulation of Li⁺/Ni²⁺ intermixing and the content of “Li O Li” configuration. The designed cathode exhibits a high initial Coulombic efficiency of about 90%, large specific capacity of 296 mAh g⁻¹ and energy density of 1047 Wh kg⁻¹ at 0.2 C, and a superior rate capability of 222 mAh g⁻¹ at 5 C with a good capacity retention of 85.7% even after 500 cycles. And the operating voltage is increased without compromising the high-capacity advantage. Such improved electrochemical performances primarily result from the band shift of the TM 3d-O 2p and non-bonding O-2p to lower energy, which would decrease Li⁺ diffusion activation energy and increase oxygen vacancy forming energy, finally improving the Li⁺ diffusion kinetics and stabilizing lattice oxygen. Moreover, the increased “Li O Li” configuration in the Li₂MnO₃ phase via increasing the Mn concentration can increase the reversible capacity to offset the negative effect of inactive doping and Li⁺/Ni²⁺ intermixing. This strategy of modulating the local electronic structure of LLOs provides great potential to design high-energy-density Li-ion batteries.     

Unveiling the Anionic Redox Chemistry in Phosphate Cathodes for Sodium-Ion Batteries

Anionic redox chemistry has aroused increasing attention in sodium-ion batteries (SIBs) by virtue of the appealing additional capacity. However, up to now, anionic redox reaction has not been reported in the mainstream phosphate cathodes for SIBs. Herein, the ultrathin VOPO₄ nanosheets are fabricated as promising cathodes for SIBs, where the oxygen redox reaction is first activated accompanied by reversible ClO₄⁻ (from the electrolyte) insertion/extraction. As a result, the VOPO₄ cathode harvests a record-high capacity (168 mAh g⁻¹ at 0.1 C) among its counterparts ever reported. Moreover, the ClO₄⁻ insertion efficiently expands the interlayer spacing of VOPO₄ and accelerates the ion diffusion, enabling an unprecedentedly high rate performance (69 mAh g⁻¹ at 30 C). Via systematic ex situ characterizations and theoretical computations, the anionic redox chemistry and charge storage mechanism upon cycling are thoroughly elucidated. This study opens up a new avenue toward high-energy phosphate cathodes for SIBs by triggering anionic redox reactions.     

Tuning Anionic Redox Activity and Reversibility for a High‐Capacity Li‐Rich Mn‐Based Oxide Cathode via an Integrated Strategy

When fabricating Li‐rich layered oxide cathode materials, anionic redox chemistry plays a critical role in achieving a large specific capacity. Unfortunately, the release of lattice oxygen at the surface impedes the reversibility of the anionic redox reaction, which induces a large irreversible capacity loss, inferior thermal stability, and voltage decay. Therefore, methods for improving the anionic redox constitute a major challenge for the application of high‐energy‐density Li‐rich Mn‐based cathode materials. Herein, to enhance the oxygen redox activity and reversibility in Co‐free Li‐rich Mn‐based Li_1.2Mn_0.6Ni_0.2O₂ cathode materials by using an integrated strategy of Li₂SnO₃ coating‐induced Sn doping and spinel phase formation during synchronous lithiation is proposed. As an Li⁺ conductor, a Li₂SnO₃ nanocoating layer protects the lattice oxygen from exposure at the surface, thereby avoiding irreversible oxidation. The synergy of the formed spinel phase and Sn dopant not only improves the anionic redox activity, reversibility, and Li⁺ migration rate but also decreases Li/Ni mixing. The 1% Li₂SnO₃‐coated Li_1.2Mn_0.6Ni_0.2O₂ delivers a capacity of more than 300 mAh g^?1 with 92% Coulombic efficiency. Moreover, improved thermal stability and voltage retention are also observed. This synergic strategy may provide insights for understanding and designing new high‐performance materials with enhanced reversible anionic redox and stabilized surface lattice oxygen.     

π‐Conjugation Enables Ultra‐High Rate Capabilities and Cycling Stabilities in Phenothiazine Copolymers as Cathode‐Active Battery Materials

In recent years, organic battery cathode materials have emerged as an attractive alternative to metal oxide–based cathodes. Organic redox polymers that can be reversibly oxidized are particularly promising. A drawback, however, often is their limited cycling stability and rate performance in a high voltage range of more than 3.4 V versus Li/Li⁺. Herein, a conjugated copolymer design with phenothiazine as a redox‐active group and a bithiophene co‐monomer is presented, enabling ultra‐high rate capability and cycling stability. After 30 000 cycles at a 100C rate, >97% of the initial capacity is retained. The composite electrodes feature defined discharge potentials at 3.6 V versus Li/Li⁺ due to the presence of separated phenothiazine redox centers. The semiconducting nature of the polymer allows for fast charge transport in the composite electrode at a high mass loading of 60 wt%. A comparison with three structurally related polymers demonstrates that changing the size, amount, or nature of the side groups leads to a reduced cell performance. This conjugated copolymer design can be used in the development of advanced redox polymers for batteries.     

Comprehensively Strengthened Metal-Oxygen Bonds for Reversible Anionic Redox Reaction

Introducing anionic redox in layered oxides is an effective approach to breaking the capacity limit of conventional cationic redox. However, the anionic redox reaction generally suffers from excessive oxidation of lattice oxygen to O₂ and O₂ release, resulting in local structural deterioration and rapid capacity/voltage decay. Here, a Na_0.71Li_0.22Al_0.05Mn_0.73O₂ (NLAM) cathode material is developed by introducing Al³⁺ into the transition metal (TM) sites. Thanks to the strong Al–O bonding strength and small Al³⁺ radius, the TMO₂ skeleton and the holistic TM–O bonds in NLAM are comprehensively strengthened, which inhibits the excessive lattice oxygen oxidation. The obtained NLAM exhibits a high reversible capacity of 194.4 mAh g^-1 at 20 mA g^-1 and decent cyclability with 98.6% capacity retention over 200 cycles at 200 mA g⁻¹. In situ characterizations reveal that the NLAM experiences phase transitions with an intermediate OP4 phase during the charge–discharge. Theoretical calculations further confirm that the Al substitution strategy is beneficial for improving the overlap between Mn 3d and O 2p orbitals. This finding sheds light on the design of layered oxide cathodes with highly reversible anionic redox for sodium storage.     

Elastic Carbon Nanotube Aerogel Meets Tellurium Nanowires: A Binder‐ and Collector‐Free Electrode for Li‐Te Batteries

Rechargeable Li batteries based on group VIA element cathodes, such as tellurium, are emerging due to their capability to provide equivalent theoretical volumetric capacity density to O and S, as well as an improved activity to react with Li. Herein, bifunctional and elastic carbon nanotube (CNT) aerogel is fabricated to combine with Te nanowires, yielding two types of binder/collector‐free Te cathodes to assemble Li‐Te batteries. The CNTs with high electronic conductivity and hollow porous structure enable stable electric contact and fast transportation of Li⁺, while trapping Te and Li₂Te in its network, triggering fast and stable Li‐Te electrochemistry. Both cathodes are also provided with fine compressibility, helping to buffer their volume changes during lithiation/delithiation and improving electrode integrity. Both cathodes deliver high specific capacity, fine cycling stability, and favorable high‐rate capability, proving their competence in building high‐energy rechargeable Li‐ion batteries.     

Accelerated Li+ Desolvation for Diffusion Booster Enabling Low-Temperature Sulfur Redox Kinetics via Electrocatalytic Carbon-Grazfted-CoP Porous Nanosheets

Lithium–sulfur (Li–S) batteries are famous for their high energy density and low cost, but prevented by sluggish redox kinetics of sulfur species due to depressive Li ion diffusion kinetics, especially under low-temperature environment. Herein, a combined strategy of electrocatalysis and pore sieving effect is put forward to dissociate the Li⁺ solvation structure to stimulate the free Li⁺ diffusion, further improving sulfur redox reaction kinetics. As a protocol, an electrocatalytic porous diffusion-boosted nitrogen-doped carbon-grafted-CoP nanosheet is designed via forming the N Co P active structure to release more free Li⁺ to react with sulfur species, as fully investigated by electrochemical tests, theoretical simulations and in situ/ex situ characterizations. As a result, the cells with diffusion booster achieve desirable lifespan of 800 cycles at 2 C and excellent rate capability (775 mAh g⁻¹ at 3 C). Impressively, in a condition of high mass loading or low-temperature environment, the cell with 5.7 mg cm⁻² stabilizes an areal capacity of 3.2 mAh cm⁻² and the charming capacity of 647 mAh g⁻¹ is obtained under 0 °C after 80 cycles, demonstrating a promising route of providing more free Li ions toward practical high-energy Li–S batteries.     

Prussian Blue@C Composite as an Ultrahigh‐Rate and Long‐Life Sodium‐Ion Battery Cathode

Rechargeable sodium ion batteries (SIBs) are surfacing as promising candidates for applications in large‐scale energy‐storage systems. Prussian blue (PB) and its analogues (PBAs) have been considered as potential cathodes because of their rigid open framework and low‐cost synthesis. Nevertheless, PBAs suffer from inferior rate capability and poor cycling stability resulting from the low electronic conductivity and deficiencies in the PBAs framework. Herein, to understand the vacancy‐impacted sodium storage and Na‐insertion reaction kinetics, we report on an in‐situ synthesized PB@C composite as a high‐performance SIB cathode. Perfectly shaped, nanosized PB cubes were grown directly on carbon chains, assuring fast charge transfer and Na‐ion diffusion. The existence of [Fe(CN)₆] vacancies in the PB crystal is found to greatly degrade the electrochemical activity of the Fe^LS(C) redox couple via first‐principles computation. Superior reaction kinetics are demonstrated for the redox reactions of the Fe^HS(N) couple, which rely on the partial insertion of Na ions to enhance the electron conduction. The synergistic effects of the structure and morphology results in the PB@C composite achieving an unprecedented rate capability and outstanding cycling stability (77.5 mAh g^?1 at 90 C, 90 mAh g?¹ after 2000 cycles at 20 C with 90% capacity retention).     

Optimizing Both Bulk and Surface Structure of Li-Rich Layered Cathodes for Long-Life and Safe Li-Ion Batteries

Although oxygen redox in Li-rich layered cathodes can boost the available capacity over 250 mAh g⁻¹, it also brings a rapid capacity fade upon long-term cycling and serious safety issue during thermal abuse. To circumvent these problems, an integrated strategy via interlayer regulation at surface and the delocalization of Li₂MnO₃-like domain on bulk is proposed. The controllable interlayer by atomic layer deposition can maximize the coating effects on elimination of the lattice mismatch to inhibit the structural degradation during cycling. And the delocalized Li₂MnO₃-like domain through compositional control can fully prohibit lattice oxygen release from the bulk to improve the thermal stability of electrode. The optimized cathode material exhibits a capacity retention of 94.0% after 200 cycles. A 1.25 Ah multilayer pouch cell with the cathode and graphite anode delivers an outstanding cycling performance that retains 80.4% of its capacity at 0.5 C after 710 cycles. More importantly, the distinguished safety features derived from the method are verified after successfully passing practical-level thermal safety and nail penetration test.     

Crystallographic Insight of Reduced Lattice Volume Expansion in Mesoporous Cu2+-Doped TiNb2O7 Microspheres during Li+ Insertion

TiNb₂O₇ represents a promising anode material for lithium-ion batteries (LIBs), but its practical applications are currently hampered by the non-negligible volumetric expansion and contraction during the charge/discharge process and the sluggish ion/electron kinetics. A combination technique is reported by systematically optimizing the porous and spherical morphology, crystal structure, and surface decoration of mesoporous Cu²⁺-doped TiNb₂O₇ microspheres to enhance the electrochemical Li⁺ storage performance and stability simultaneously. The Cu²⁺ dopants preferentially replace Ti⁴⁺ in crystal lattices, which decreases the Li⁺ diffusion barrier and increases the electronic conductivity, as confirmed by density functional theory (DFT) calculation and demonstrated by diverse electrochemical characterizations. The successful Cu²⁺ doping significantly reduces the lattice expansion coefficient from 7.26% to 4.61% after Li⁺ insertion along the b-axis of TiNb₂O₇, as visualized from in situ and ex situ XRD analysis. The optimal 5% Cu²⁺-doped TiNb₂O₇ with surface coating of N-doped carbon exhibits significantly enhanced specific capacity and rate and cyclic performances in both half- and full-cell configurations, demonstrating an excellent electrochemical behavior for fast-charging LIB applications.     

Thermodynamic Activation of Charge Transfer in Anionic Redox Process for Li‐Ion Batteries

Anionic redox processes are vital to realize high capacity in lithium‐rich electrodes of lithium‐ion batteries. However, the activation mechanism of these processes remains ambiguous, hampering further implementation in new electrode design. This study demonstrates that the electrochemical activity of inert cubic‐Li₂TiO₃ is triggered by Fe³⁺ substitution, to afford considerable oxygen redox activity. Coupled with first principles calculations, it is found that electron holes tend to be selectively generated on oxygen ions bonded to Fe rather than Ti. Subsequently, a thermodynamic threshold is unravelled dictated by the relative values of the Coulomb and exchange interactions (U) and charge‐transfer energy (Δ) for the anionic redox electron‐transfer process, which is further verified by extension to inactive layered Li₂TiS₃, in which the sulfur redox process is activated by Co substitution to form Li_1.2Ti_0.6Co_0.2S₂. This work establishes general guidance for the design of high‐capacity electrodes utilizing anionic redox processes.     

Highly Stable Lithium−Sulfur Batteries Promised by Siloxene: An Effective Cathode Material to Regulate the Adsorption and Conversion of Polysulfides

Designing an appropriate cathode is still a challenge for lithium–sulfur batteries (LSBs) to overcome the polysulfides shuttling and sluggish redox reactions. Herein, 2D siloxene nanosheets are developed by a rational wet‐chemistry exfoliation approach, from which S@siloxene@graphene (Si/G) hybrids are constructed as cathodes in Li‐S cells. The siloxene possesses corrugated 2D Si backbone with abundant O grafted in Si₆ rings and hydroxyl‐functionalized surface, which can effectively intercept polysulfides via synergistic effects of chemical trapping capability and kinetically enhanced polysulfides conversion. Theoretical analysis further reveals that siloxene can significantly elevate the adsorption energies and lower energy barrier for Li⁺ diffusion. The LSBs assembled with 2D Si/G hybrid cathodes exhibit greatly enhanced rate performance (919, 759, and 646 mAh g^?1 at 4 C with sulfur loading of 1, 2.9, and 4.2 mg cm^?2, respectively) and superb durability (demonstrated by 1000 cycles with an initial capacity of 951 mAh g^?1 and negligible 0.032% decay rate at 1 C with sulfur loading of 4.2 mg cm^?2). It is expected that the study presented here may open up a new vision toward developing high‐performance LSBs with siloxene for practical applications.     

Oxygen‐Deficient Homo‐Interface toward Exciting Boost of Pseudocapacitance

Pseudocapacitors hold great promise as charge storage systems that combine battery‐level energy density and capacitor‐level power density. The utilization of pseudocapacitive material, however, is usually restricted to the surface due to poor electrode kinetics, leading to less accessible charge storage sites and limited capacitance. Here, tin oxide is successfully endowed with outstanding pseudocapacitance and fast electrode kinetics in a negative potential window by engineering oxygen‐deficient homo‐interfaces. The as‐prepared SnO_2?x@SnO_2?x electrode yields a specific capacitance of 376.6 F g^?1 at the current density of 2.5 A g^?1 and retains 327 F g^?1 at a high current density of 80 A g^?1. The theoretical calculation reveals that the oxygen defects are more favorable at homo‐interfaces than at the surface due to the lower defect formation energy. Meanwhile, as compared with the surface, the homo‐interface possesses more stable Li⁺ storage sites that are readily accessed by Li⁺ due to the occurrence of oxygen vacancies, enabling outstanding pseudocapacitance as well as high rate capability. This oxygen‐deficient homo‐interface design opens up new opportunities to develop high‐energy and power pseudocapacitors.     

Confined Sulfur in Microporous Carbon Renders Superior Cycling Stability in Li/S Batteries

The use of sulfur in the next generation Li‐ion batteries is currently precluded by its poor cycling stability caused by irreversible Li₂S formation and the dissolution of soluble polysulfides in organic electrolytes that leads to parasitic cell reactions. Here, a new C/S cathode material comprising short‐chain sulfur species (predominately S₂) confined in carbonaceous subnanometer and the unique charge mechanism for the subnano‐entrapped S₂ cathodes are reported. The first charge–discharge cycle of the C/S cathode in the carbonate electrolyte forms a new type of thiocarbonate‐like solid electrolyte interphase (SEI). The SEI coated C/S cathode stably delivers ≈600 mAh g^?1 capacity over 4020 cycles (0.0014% loss cycle^?1) at ≈100% Coulombic efficiency. Extensive X‐ray photoelectron spectroscopy analysis of the discharged cathodes shows a new type of S₂ species and a new carbide‐like species simultaneously, and both peaks disappear upon charging. These data suggest a new sulfur redox mechanism involving a separated Li⁺/S^2? ion couple that precludes Li₂S compound formation and prevents the dissolution of soluble sulfur anions. This new charge/discharge process leads to remarkable cycling stability and reversibility.     

Achieving Synergetic Anion-Cation Redox Chemistry in Freestanding Amorphous Vanadium Oxysulfide Cathodes toward Ultrafast and Stable Aqueous Zinc-Ion Batteries

Flexible aqueous zinc-ion batteries (AZIBs) with high safety and low cost hold great promise for potential applications in wearable electronics, but the strong electrostatic interaction between Zn²⁺ and crystalline structures, and the traditional cathodes with single cationic redox center remain stumbling blocks to developing high-performance AZIBs. Herein, freestanding amorphous vanadium oxysulfide (AVSO) cathodes with abundant defects and auxiliary anionic redox centers are developed via in situ anodic oxidation strategy. The well-designed amorphous AVSO cathodes demonstrate numerous Zn²⁺ isotropic pathways and rapid reaction kinetics, performing a high reversible capacity of 538.7 mAhg^-1 and high-rate capability (237.8 mAhg^-1@40Ag^-1). Experimental results and theoretical simulations reveal that vanadium cations serve as the main redox centers while sulfur anions in AVSO cathode as the supporting redox centers to compensate local electron-transfer ability of active sites. Significantly, the amorphous structure with sulfur chemistry can tolerate volumetric change upon Zn²⁺/H⁺ insertion and weaken electrostatic interaction between Zn²⁺ and host materials. Consequently, the AVSO composites display alleviated structural degradation and exceptional long-term cyclability (89.8% retention after 20 000 cycles at 40 Ag^-1). This work can be generally extended to various freestanding amorphous cathode materials of multiple redox reactions, inspiring development of designing ultrafast and long-life wearable AZIBs.     

Combined Defect and Heterojunction Engineering in ZnTe/CoTe2@NC Sulfur Hosts Toward Robust Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) are feasible candidates for the next generation of energy storage devices, but the shuttle effect of lithium polysulfides (LiPSs) and the poor electrical conductivity of sulfur and lithium sulfides limit their application. Herein, a sulfur host based on nitrogen-doped carbon (NC) coated with small amount of a transition metal telluride (TMT) catalyst is proposed to overcome these limitations. The properties of the sulfur redox catalyst are tuned by adjusting the anion vacancy concentration and engineering a ZnTe/CoTe₂ heterostructures. Theoretical calculations and experimental data demonstrate that tellurium vacancies enhance the adsorption of LiPSs, while the formed TMT/TMT and TMT/C heterostructures as well as the overall architecture of the composite simultaneously provide high Li⁺ diffusion and fast electron transport. As a result, v-ZnTe/CoTe₂@NC/S sulfur cathodes show excellent initial capacities up to 1608 mA h g⁻¹ at 0.1C and stable cycling with an average capacity decay rate of 0.022% per cycle at 1C during 500 cycles. Even at a high sulfur loading of 5.4 mg cm^–2, a high capacity of 1273 mA h g⁻¹ at 0.1C is retained, and when reducing the electrolyte to 7.5 µL mg⁻¹, v-ZnTe/CoTe₂@NC/S still maintains a capacity of 890.8 mA h g⁻¹ after 100 cycles at 0.1C.     

Probing the Self‐Boosting Catalysis of LiCoO2 in Li–O2 Battery with Multiple In Situ/Operando Techniques

Designing high‐activity catalysts and revealing the in‐depth structure–property relationship is particularly important for Li–O₂ batteries. Herein, the self‐boosting catalysis of LiCoO₂ as an electrocatalyst for Li–O₂ batteries and the investigation of its self‐adjustment mechanism using in situ X‐ray absorption spectroscopy and other operando characterization techniques is reported. The intercalation/extraction of Li⁺ in LiCoO₂ not only induces the change in Co valence and modulates the electronic/crystal structure but also tunes the surface disorder degree, lattice strain, and local symmetry, which all affect the catalysis activity. In a discharge, highly ordered LiCoO₂ acts as a catalyst to boost oxygen reduction reaction. During charging, the initial extraction of Li⁺ from LiCoO₂ induces Li/oxygen vacancy and Co⁴⁺, which deforms CoO₆ octahedron as well as lowers the symmetry, and accordingly promotes oxygen evolution reaction. This article offers insights into tuning the activity of catalysts for Li–O₂ batteries with the intercalation/extraction of alkali metal ions in traditional cathodes.     

3D Carbon Nanotube Network Bridged Hetero‐Structured Ni‐Fe‐S Nanocubes toward High‐Performance Lithium,Sodium, and Potassium Storage

Lithium‐ion, sodium‐ion, and potassium‐ion batteries have captured tremendous attention in power supplies for various electric vehicles and portable electronic devices. However, their practical applications are severely limited by factors such as poor rate capability, fast capacity decay, sluggish charge storage dynamics, and low reversibility. Herein, hetero‐structured bimetallic sulfide (NiS/FeS) encapsulated in N‐doped porous carbon cubes interconnected with CNTs (Ni‐Fe‐S‐CNT) are prepared through a convenient co‐precipitation and post‐heat treatment sulfurization technique of the corresponding Prussian‐blue analogue nanocage precursor. This special 3D hierarchical structure can offer a stable interconnect and conductive network and shorten the diffusion path of ions, thereby greatly enhancing the mobility efficiency of alkali (Li, Na, K) ions in electrode materials. The Ni‐Fe‐S‐CNT nanocomposite maintains a charge capacity of 1535 mAh g^?1 at 0.2 A g^?1 for lithium ion batteries, 431 mAh g^?1 at 0.1 A g^?1 for sodium ion batteries, and 181 mAh g^?1 at 0.1 A g^?1 for potassium‐ion batteries, respectively. The high performance is mainly attributed to the 3D hierarchically high‐conductivity network architecture, in which the hetero‐structured FeS/NiS nanocubes provide fast Li⁺/Na⁺/K⁺ insertion/extraction and reduced ion diffusion paths, and the distinctive 3D networks maintain the electrical contact and guarantee the structural integrity.